Production of ethylene chlorohydrin



April 8, 1958 B. H. NlcoLAlsEN PRODUCTION OF ETHYLENE vOHLOl-'eOHYDRINFiled May '7. 1953 INVENTOR BER/VA RD H /V/com /E/v MQLMW n@ ATTORNEYSUnited States ,Patent 2,830,095 rRoDUcrroN or ETHYLENE CHLoRoHYDRlNApplication May 7, 1953, Serial No. 353,658

8 Claims. (Cl.V 260-634) This invention relates to the production ofolefin chlorohydrins, especially ethylene chlorohydrin. Moreparticularly it relates to improvements in the yield of product bycontrol of the concentrationA of by-product olefin dichloride in thereaction liquor.

Prior processes of producing ethylene chlorohydrin usually compriseintroducing a stream of olefin-bearing gas and a stream of chlorineseparately into a body of water in a suitable reactor. In general, thestream of ethylene is diluted with saturated hydrocarbons such asmethane or other inert gases, the mixed gas containing up to about 40-mole percent of ethylene. AA suitable proportion of chlorine to reactwith the ethylene contained in the gas and to produce a chlorohydrinsolution of about 6 percent concentration is introduced.' Extensiveoperations of distillation or extraction are 'necessaryV in order toobtain relatively concentrated solutionsof ethylene chlorohydrin or pureanhydrous ethylene chlorohydrin. Ethylene dichloride, always formedrinthe re-' action mixture as a by-product, usually forms av separate phasedispersed `in the aqueous reaction medium.

Whenever an attempt is made to use afrelatively Vconcentrated ethylenegas containing, for example, 50vrnoleV percent or more of ethylene or toreduce the proportion o-f water introduced, or 'to recycle the aqueousliquorV in an effort to obtain chlorohydrin solutions ofgreaterconcentrations, numerous difficulties are encountered.' The proportionof ethylene dichloride formed usually in creases and its presenceappears to favor the formation of additional quantities. Concomitantly,the chlorohy`v drin yield decreases. My process permits manufacture ofrelatively concen-l trated chlorohydrin solutions of up to 12 percentVor more using rich ethylene gas as feed. YieldsV are 80 percent or moreand conversions are high by carefully vrestricting formation andconcentration 'of ethylenerdichloride. .'As a result, the size of the.necessary.' equipment,y and Yatccordingly the expense, is considerablyreduced.' The chlorohydrination reaction is carried out in a plu-"-rrality of stages arranged at least partly inset-ies. Water i isintroduced into the last stage reactorand'flows counterstage to the richethylene gas introduced to the Yfirst stagel reactor. The reactors areadvantageously tubular in character and the gases dissolve and react in'the'flowing.v stream of water. Ethylene dichloride is electively abetter,

' benecial in ethylene dichloride removal.

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geous. Y

The yield of ethylene chlorohydrin, I have found, depends directly onthe ethylene dichloride content of the reaction liquor. VBy this Imeannot merely separate phase ethylene dichloride but more importantdissolved ethylene dichloride. The content of ethylene dichloride inturn is dependent on the purity of the ethylene charged and the extentof dilution with other gases, the chlorohydrin concentration, thereactor pressure and temperature` and the extent to which ethylenedichloride is removed from the gas between stages. Primarily all ofthese factors but the last are pre-established by economic and designconsideration basedupon the nature of the hydrocarbon feed gasavailable, the feed-fractionation facilities and the process design.that multi-stage reaction with interstage removal of ethyl,-

ene dichloride from the gas stream effectively reducesl the ethylenedichloride concentration in the reaction liquor. stream, moreover, isdirectly dependent upon conditions of temperature and pressure in theinterstage treating zone. Y Reduced temperature benets the removaltreatment, but also reduced pressure in the reaction zone is The effectof the interstage treatment is to reduce the ethylene dichloride contentof the gas and therefore of the liquor. Maintenance of the ethylenedichloride content of the.

reaction liquor at less than about 0.35 weight percentv is essential in'order to obtain yields of over90 percent,

scrubbed from the reaction liquor in the reactors by' the f 50 l,at a.temperature of 0-20 C., the ethylene dichloride content of the reactorliquor is maintained below about gas stream which is treated betweenstages to remove" ethylene dichloride. Also the efuent liquor fromtherst stage is advantageously treated to remove residual ethylenedichloride and then may be utilized as such or may be treated forrecovery Vof concentrated ethylene` chlorohydrin. reaction liquor entersthe next stage. p i ,Y Ethylene dichloride may be removed from .the'gas4 stream by physical or physico-chemical methods.l For, example, thegas stream may be refrigerated to cause separation of ethylenedichloride. Treatment'by absorp-y tion or adsorption, however, with orwithout cooling, is

Additional chlorine is introduced as the, t

0 -cooling ,or scrubbing the reactor gas between stagesgheY Thuswithinterstage treatment by temperature reduction to less thanabout 20C.land pressure control at about 20-35 p. s.'i. lg.,or with mechanicalor chemicalremoval by absorption or adsorption, the ethylenedichloride'content of the reaction liquor is maintained below 0.35 per-vcent and yields of better than 90 percent are obtainedconsistently.y

To obtain the advantages of the process it'is desirable Vto controlreactor pressure from about 10 to about 100.,

p. s. i.V g. Using a tubular reactor, the tube diameter may vary fromabout V1.5 to 4 inches in diameter. Although larger tubes can be used,they are more expensive than is usually justifiable.

actors may be used in series; The feed gas may contain from about 50 to95 mole percent of ethylene. Reactor temperatures may vary from about25`to 80 C. A minimum of two reaction stages should be used.

To obtain yields of 90-95 percent of ethylene chlorohydrin it isdesirableto maintain these variablesA within theselimits. Specialadvantages however can beirealized when the feed gas contains about -90mole per-,

cent of ethylene and the gas is introducedrat a pressure Y o fv 35 to 45p. s. i. g. to the first of two reactors arranged 'in series. Theaqueous liquor then may ilow through the tubes at about 5 feet persecond with tubes of about 4- inches in diameter. Under these conditionswith an interstage gas cooler operating at 25-35 p. s. i. g. and v 0.35percent and yields of over percent may be consistently obtained. Underclosely controlled conditions of operation, yields of about 97 percentof ethylene chlorohydrin may be obtained by maintaining Aan ethylene di-:chloride concentration in the reactor liquor below about 0.08 percent.

YWhen the ethylene dichloride content is reduced by ultimate yield ofethylene chlorohydrin maybe expressed as a function of the pressure andtemperature of the inter- Patented Apr. 8, 1958 Thus, an oil scrubbermay be used or a passage overv activated carbon orother adsonbents isadvanta- I have found however;

Removal of ethylene dichloride from the gas.

A suitable velocity of flow' of the reaction liquor in the tubes isabout 3 to17 feet` per second. Alternatively, conventional tank type re.

stage ethylene dichloride removal operation, provided other factors, e.g. ethylene concentration and chlorohy- Vliquid velocityl was 5 feet persecond. Chlorine was in- 50 percent ethylene (dry basis), test data showthat yields approximating 90-95 percent of chlorohydrin may be obtainedby operating an interstage cooler at-about 25-40 p. s. i. g. and between0 and 30 C. ln addition, signicantly higher yields are obtained byinterstage absorption or adsorption as compared to the use of the cooleralone. Absorption or adsorption is particularlyadvantageous in thatethylene dicldoride may be more effectively removed without thenecessity of reducing the temperature of the stream.

As shown in the flowplan of the accompanying drawing water is pumped bylines and 11 through tubular reactor 12. Chlorine is injected throughconnection 13 and approximately 8() percent ethylene gas stream from therst stage is injected vfrom line 14. The reaction l mixture isdischarged from second stage reactor 12 through line 15 into a settler16. Spent gas is removed from settler 16 by line 17 controlled by valve29 which maintains the operating pressureV on the system. The reactionliquor is pumped by means of pump 35Y in line 18 and the etlluent isdivided between valvcd lines 18 and 11 to control the proportion ofliquor recycled to the second stage reactor and charged to the tirststage reactor 19. Chlorine is injected by means of connection 20 andapproximately 90 percent feed gas is injected by means of connection 21.The etiluent from rst stage reactor 19 is discharged through line 22into a settler 23.` Thereaction liquor is withdrawn through line 24 `andmay be partly recycled through line 33 and` wholly or partly removed asproduct through line 34. The Vfirst stage eluent gas is passed byline25- to caustic scrubber 26 and thence by line'27 through cooler 28andlinev30-discharging into `the ethylenedichloride separating .unit 31.The temperature of the gas stream may be controlled by passing all or aportion of the stream throughvalved bypass line 32 or throughrefrigeration cooling -section 28. The ethylene dichlorideseparatingunit is diagrammati-` cally shown and may represent theknock-out drum following the refrigeration equipment or it may representa tower packed with an adsorbent material'such as activatedv charcoal,silica gel, alumina and the like. Alternatively, ethylene dichlorideseparating unit 31may represent an absorption system in which theentering gas stream is scrubbed by countercurrent tlow through a packedtower through which a solvent for ethylene dichloride is introduced.Advantageously, a petroleum solvent of the aliphatic type may beemployed.

Example I During a run of about 3 hours, 73.9 pounds of ethylene dilutedwith 16.6 pounds of nitrogento give a mixture containing 79.3 molespercent of ethylene was introduced into a flowing stream of aqueousliquor in a tubular reactor system. Dunng the run 3843 pounds of waterwas introduced and continuously recycled at a superficial liquidvelocity of 5 feet per second through the reactor. Chlorine wasintroduced at a point upstream from the ethylene inlet. The reactortemperature was 44 C. and the pressure was 48.6 p. s. i. g. In theinterstage cooler a temperature of 26 C. was maintained and the pressurewas 37.6 p. s. i. g. Ethylene dichloride concentration in thecirculating liquor averaged 0.06% and the total formed was 3.7 pounds.'l` he weight and yield of ethyleneichlorohydrin were about 160 poundsand 97.4%, respectively.

Example II A lmixture of about 160 pounds` of ethylene "and 35.8 poundsof nitrogen was introduced into thetubular reactor of Example I with9025 pounds of water. The supercial troduced as beforey and the reactorwas maintained `at about 54 C. The interstage cooler was operated at19.3 C. and at 38 p. s.'i. g. to maintain an ethylene dichlorideconcentration inthe liquor of 0.07%. The weight of ethylene dichlorideformed was 3.58 pounds. Ethylene chlorohydrin yield was 97.8% and theethylene conversion was 94.1%.

Example III A gas mixture simulating that obtainable from such ascrubber operation as described in Example II and comprising 122 poundsof ethylene'and 3.96 pounds of ethyl- Vene dichloride was diluted with26.4 pounds of nitrogen stage and liquid passing from the second stageto the rstV stage, controlling the concentration of ethylene in the feed`gas at -95 mole percent, the reaction temperature between about 25-80C. and the reaction pressure between about 10 to 100 p. s. i. g.,removing theethylene gas stream between the stages, treating it forremoval of ethylene dichloride, and injecting the treated gas into thesecond stage whereby the treated gas scrubs ethylene dichloride from thereaction liquor in the second stage thereby providing desirable reactionconditions in the second stage and conditioning the reaction liquor foruse in the first stage.

2. In the production of ethylene chlorohydrin by chlorohydrination ofethyl-ene in an aqueous system, the method which comprises conductingthe reaction in a plurality of serially connected gas-liquid `reactionstages including a first stage and a second stage, ethylene gas `andliquid flowing countercurrently between the stages, ethylene gas passingfrom the first stage to the second stage and liquid passing from thesecond stage to the iirst stage,

f controlling the concentration of ethylene in the `feed gas at 50495mole percent, the reaction temperature between i about 2 5- 80 C.andthereaction pressure between about 10 to 100 p.` s. i. g., removingthe ethylene' gas stream bctween the stages, treating it for removal ofethylene dichloride, and injecting the Atreated gas into the` secondstage whereby the treated gas scrubs ethylene dichloride from thereaction liquor in the second stage thereby providing desirable reactionconditions in the second stage and conditioning the reaction liquor foruse in the rst stage, the extent. of ethylene dichloride removal beingcontrolled to maintain less than about 0.35% by weight ethylenedichloride inthe first and second stage reaction liquorethylenedichloride removal is conducted by contacting the gas stream with anabsorbent medium.

7. The process of claim 2 in which the treatment of ethylene dichlorideremoval Ais conducted by contacting the gas stream with analiphaticftype petroleum solvent.

8. The process of claim 2 in which the treatment for ethylene dichlorideremoval is conducted by cooling the reaction gas stream to less thanabout 20 C. while maintaining a pressure of about 20 to 35 p. s. i. g.

References Cited in the le of this patent UNITED STATES PATENTS YoungMay 29, Archibald Dec. 9, Neuhaus Sept. 4, Knaus Nov. 6,

1. IN THE PRODUCTION OF ETHYLENE CHLORHYDRIN BY CHLOROHYDRINATION OFETHYLENE IN AN AQUEOUS SYSTEM, THE METHOD WHICH COMPRISES CONDUCTING THEREACTION IN A PLURALITY OF SERIALLY CONNECTED GAS-LIQUID REACTION STAGESINCLUDING A FIRST STAGE AND A SECOND STAGE, ETHYLENE GAS AND LIQUIDFLOWING COUNTERCURRENTLY BETWEEN THE STAGES, ETHYLENE GAS PASSING FROMTHE FIRST STAGE TO THE SECOND STAGE AND LIQUID PASSING FROM THE SECONDSTAGE TO THE FIRST STAGE, CONTROLLING THE CONCENTRATION OF ETHYLENE INTHE FEED GAS AT 50-95 MOLE PERCENT, THE REACTION TEMPERATURE BETWEENABOUT 25-80*C. AND THE REACTION PRESSURE BETWEEN